Figure 2

Representative images of PrP ^Sc deposition in the midbrain of tg338 mice after challenge with scrapie. The deposition patterns observed were characteristic of strains G₃₃₈ (a), Apl₃₃₈ii (b) and Cag₃₃₈ (c). Three mice showed phenotypic characteristics typical of both G₃₃₈ and Apl₃₃₈ii patterns; photos d-f are all from a single mouse showing small discrete aggregates (d, red arrow) in the habenular bodies which is a G₃₃₈ characteristic feature in addition to plaques and large aggregates in subpial areas (d, black arrow; e, periaqueductal grey matter; f, lateral ventricle) which are associated with Apl₃₃₈ii. In a single mouse with Apl₃₃₈ii phenotype, punctate and prominent intraneuronal labelling (g) which are features associated with the P₃₃₈ pattern were also observed; the Apl₃₃₈ii phenotype is not usually associated with intraneuronal labelling (h). The neurons in g and h are located in the olive nucleus. Scale bar in a-c represents 250 μm; d–f 100 μm; g and h 25 μm.